below i will use the formula given by hugh to demostrate how much more power can be made by increasing the wind speed....i will use 10' diameter blades, and 10,15, and 20 mph wind speeds.
.the formula: blade power(in watts=0.15xblade diameter(squared)xwindspeed(cubed)
(in meters) (in meters per second)
10 mph example power in watts =0.15x3.05(squared)x4.5(cubed)
=127.1 watts
15 mph example power in watts = 0.15x3.05(squared)x6.71(cubed)
=421.4 watts
20 mph example power in watts = 0.15x3.05(squared)x8.9(cubed)
=983 watts
CONCLUSION: 10' blade x 10 mph wind =127.1 watts
10' blade x 15 mph wind =421.4 watts
10' blade x 20 mph wind =983 watts
There is a substantial increase of power created with a 10 mph increase of wind speed.........pickster